Carbide Materials Research Articles

Effect of chromium doping on the grain boundary character of WC-Co

The life of cutting tool inserts is critically important for efficient machining, reducing manufacturing cost, embedded energy, and enabling more complex parts to be machined. For these applications, cemented carbide (WC-Co) materials are a prime candidate. The performance of these materials can be limited by early fracture, typically via an intergranular fracture path with respect to carbide grains. This motivates further studies to understand the character of the grain boundary network so that grain boundary engineering (GBE) of WC-Co tools can be used to improve tool life and performance. In this work, we have used Rohrer et al.'s five-parameter grain boundary character distribution (GBCD) analysis to examine the grain boundary network of WC-10wt%Co and WC-10wt%Co-1wt%Cr samples (Rohrer et al., 2004a [1]). It was found that the measured area fraction of the Σ2 boundaries was comparable to the values reported in the literature despite the relatively larger grain sizes (∼14 μm) and higher cobalt contents. The result suggests that chromium doping increases the area fraction of Σ2 boundaries from 12.8 % to 14.8 %. It is proposed that this is a consequence of altering the Σ2 boundary energy, as associated with adding chromium.

Boron carbide biodevices for disease-specific biomarker detection: a theoretical study

An effective approach for early diagnosis of lung cancer involves detecting its biomarkers in the patient’s exhaled breath. Acetone was identified as a vital biomarker, showing significant elevation in lung cancer. Two-dimensional boron carbide materials offer benefits such as resistance to high temperatures, stability, and excellent sensitivity toward toxic gas molecules. Here, we explore acetone adsorption on the pristine and transition metal (TM)-doped (Sc, Ti, V, Cr, and Mn) boron carbide monolayers (BCMs) with density functional theory calculations. Our results revealed that the V-, Cr-, and Mn-doped BCM show larger adsorption energy values as compared to the pristine BCM surface. The change of band gap energy of surfaces after acetone adsorption is obtained between 55 and 275%. The work function variation of studied monolayers upon acetone adsorption has been also investigated and results show that V-, Cr-, and Mn-doped BCM systems are sensitive to acetone gas molecules. This work suggests that BCM-based layers can be used as a biosensor to identify VOC biomarkers such as acetone.

Investigation of the physical properties through strain effect of monolayer silicon carbide material: DFT analysis

Researchers have shown considerable interest in two-dimensional silicon carbide recently because of its relatively high exciton binding energy and wide bandgap. This article focuses on analyzing and studying first-principles density functional theory to assess the influence of strain on the phonon, mechanical, optical, and electronic characteristics of SiC. Additionally, we investigate the band structure for spin-orbit coupling. The SiC exhibits an indirect bandgap, but applying tensile strain it shows a direct bandgap. Although the bandgap decreases under tensile stresses and the SOC effect, it increases when exposed to compressive pressures. Furthermore, the optical characteristics of single-layer SiC, such as the refractive index, electron energy loss spectra, dielectric spectra, and absorption coefficient, showcase its remarkable capacity to effectively absorb light in both the visible and infrared (IR) regions. SiC exhibits dynamic and mechanical stability under compressive strain up to −3% and under tensile strain up to +6.

Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions

PTFE coatings were deposited on YT15 carbide substrates using spray technology. A series of examinations were conducted, including the use of surface and cross-section micrographs to analyze the structural integrity of the coatings. The surface roughness, the adhesion force between the PTFE coatings and the carbide substrate, and the micro-hardness of the coated carbide were also evaluated. Additionally, the friction and wear behaviors were assessed through dry sliding friction tests against WC/Co balls. The test results indicated that while the PTFE-coated carbide exhibited a rougher surface and reduced micro-hardness, it also demonstrated a significant reduction in surface friction and adhesive wear. These findings suggest that the PTFE coatings enhance the overall wear resistance of the carbides. The lower surface hardness and shear strength of the coatings influenced the friction performance, leading to specific wear failure mechanisms, such as abrasion wear, coating delamination, and flaking. Overall, the deposition of PTFE coatings on carbide substrates presents a promising strategy to enhance their friction and wear performance. This approach not only improves the durability of carbide materials but also offers potential applications in industries where reduced friction and wear are critical for performance.

Densification and properties of WC-CoCrFeNi/Co cemented carbide fabricated via spark plasma sintering

The spark plasma sintering (SPS) technique was used to employe WC-CoCrFeNi/Co cemented carbides, incorporating CoCrFeNi and Co as low-coercivity binder phases, resulting in the development of cemented carbides with exceptional mechanical properties. The densification mechanism varying with increasing sintering temperature and the effect of densification on the mechanical properties were investigated using the creep deformation model. In the temperature range of 1100 °C–1300 °C, the main factors contributing to densification behavior are particle rearrangement and grain boundary diffusion due to the viscous flow of the binder phase. The densification mechanism gradually transforms into dislocation climbing with increasing temperature. When the sintering temperature exceeded 1300 °C, the WC grain size increased significantly with increasing temperature and holding time, and the dominant mechanism for grain growth was grain boundary diffusion. The high densification resulted in a substantial increase in effective grain boundary area, thereby increasing both hardness and fracture toughness of the material. Benefiting from the fine grain strengthening effect of the high-entropy alloys (HEAs) and the excellent wettability of Co, a highly dense cemented carbide material with excellent hardness and fracture toughness is achieved at the sintering temperature of 1300 °C, characterized by a relative density of 99.3 %, a hardness of 2064.9 MPa, and a fracture toughness of 11.5 MPa m−2.

Synthesis and oxidation behavior of Ti-Zr-Ta(Hf) high entropy carbide nanopowders by sol-gel method

Multi-component solid solution carbide is a promising material due to its excellent mechanical strength, thermal stability, and resistance to chemical corrosion. In this study, we intentionally designed and synthesized three types of solid solution carbide powders using the sol-gel method: (Ti1/3Zr1/3Ta1/3)C, (Ti1/3Zr1/3Hf1/3)C and (Ti1/4Zr1/4Ta1/4Hf1/4)C. The results show that the liquid-phase precursor undergoes pyrolysis at 800 °C and subsequently form homogeneous single face-centered cubic structure solid solutions upon thermal treatment at temperatures exceeding 1800 °C. The obtained powders exhibited ultra-fine and uniform particle sizes of 340 nm, 248 nm, and 401 nm, respectively. Furthermore, the oxidation behavior of the three types of carbide powders in air shows that Hf and Ta elements are of great significance in improving oxidation resistance. The solid solution of Hf increases the initial oxidation temperature, while Ta tends to form a complex oxide with Zr, which helps to improve the oxidation temperature resistance. This work therefore contributes filling the gap of employing the sol-gel method in the fabrication of multi-component solid solution carbide materials and provides novel insights into their synthesis mechanism and oxidation behaviours.

Dry Sliding Wear Behavior of Cemented Carbide at Elevated Temperatures

The material for a cutting tool needs to be carefully selected to withstand high temperatures during cutting and have good wear performance. The use of cutting tools made from cemented carbide material was studied due to its potential in terms of mechanical properties that are ideal at high temperatures up to 1000 °C and being cheaper than other materials. This investigation of the dry wear of this cutting material focused on temperatures of 25 °C, 200 °C, and 300 °C, with loads of 50 N, 100 N, and 150 N. The weight loss, friction coefficient, and change of the pin microstructure were determined. It was found that the higher the temperature and load applied to the cemented carbide pin, the more the microstructure changed, and the percentage of weight loss increased up to 0.55%. The wear rate on the cemented carbide pins was higher when applied to a stainless steel disc compared to a mild steel disc. The simulation revealed that the von Mises stress on the stainless steel disc was 51.759 Pa, while that on the mild-steel disc was 60.379 Pa. This indicates that both materials did not fail because the von Mises stress was lower than the disc yield stress.

The effect of Titanium Carbide (TiC) addition on the performance of Cupro-Tungsten (Cu-W) alloy for spark erosion electrodes used in machining carbide materials

This article focuses on the development and characterization of Copper-Tungsten (WCu) electrodes, enhanced with the addition of nickel and cobalt as activators and titanium carbide (TiC) for improved wear resistance. The electrodes were manufactured using powder metallurgy through cold pressing, followed by sintering-infiltration at 1250°C under a reducing atmosphere of H2. The characterization process involved measuring density, microhardness, electrical conductivity, and SEM/EDX microstructure. Additionally, technological tests were conducted on P35 carbide parts to assess parameters such as material removal rate (MRR), tool wear rate (TWR), and wear rate (WR). The results indicated that the W-Cu-Ni-TiC compact exhibited an improved density of 11.95, while the W-Cu-Co-TiC compact demonstrated the highest MRR. The W-Cu-Co-TiC compact also recorded a lower TWR. Overall, the W-Cu-Co-TiC compact offered the best compromise in terms of electrode-part wear, achieving superior microhardness values of 289Hv. These findings suggest that incorporating transition elements and TiC into WCu electrodes can significantly enhance their performance, making this study a valuable reference for future research aimed at improving electrode wear resistance through material and manufacturing advancements.

Use of RSM desirability approach to optimize WEDM of mild steel

Wire Electrical Discharge Machining (WEDM) is a non-traditional material removal process commonly used for precision machining of hard materials such as super alloys, ceramics, carbide, and composite materials. Optimization of process parameters is critical for improving machining efficiency and achieving the desired surface quality. Response Surface Methodology (RSM) systematically optimizes process parameters and investigates their impact on machining performance. WEDM control parameters such as pulse ON Time (TON) (50–60 μs), pulse OFF Time (TOFF) (25–34 μs), gap voltage (VG) (25–250 V), peak current (IP) (1–6 A), and dielectric flow rate (Df) (1–3 LPM) are optimized to reduce surface roughness (SR) and taper angle (TA) while increasing material removal rate (MRR) during the machining of Mild Steel. The optimal parameters are TON as 53 μs, TOFF as 28 μs, IP as 2.65 A, VG as 185 V, and Df as 1.5 LPM. The experimental findings are presented to demonstrate the usefulness of the proposed strategy in optimizing WEDM control parameters. The validation test was conducted under optimal conditions and the results were reported. The manufacturing industries can use RSM optimization in the manufacturing domain.

Influence of applied tensile/compressive stress on He-irradiated SiC: Examining defect evolution through experimental investigation and DFT simulations

This study investigates the effects of applied tensile and compressive stresses on the evolution of defects in He-irradiated silicon carbide (SiC) materials. By combining experimental studies with density-functional theory (DFT) simulations, we systematically analyzed the microstructural changes and defect formation mechanisms in SiC under stress. The research focused on He irradiation of SiC at 750 °C, with a fluence of 1 × 101⁷ He/cm2. The results revealed that the strain resulting from radiation damage depends on the applied stress during irradiation. Moreover, the formation of platelets is influenced by this applied stress: tensile stress promotes platelet growth, while compressive stress inhibits it. DFT simulations further supported these experimental findings by showing that under tensile strain, both carbon vacancies (Cv) and He atoms exhibit low energy barriers for migration. This phenomenon facilitates platelet growth, aligning well with the observations made in the experiments. However, when considering applications like semiconductor thin film transfer, such as the Smart-cut technique, He implantation under tensile stress can actually be advantageous. This approach enables the use of lower He fluence, which in turn reduces the overall cost of the operation. By strategically leveraging the effects of tensile stress on He implantation, it becomes possible to optimize processes like Smart-cut for more efficient and cost-effective thin film transfer in semiconductor manufacturing.

Removal mechanism and hole quality of SiCp/Al composites by ultrasonic elliptical vibration-assisted helical milling

SiCp/Al composites are widely used in the aerospace field due to their excellent properties. However, the huge difference in the properties of silicon carbide and aluminum matrix materials can easily lead to machining defects. Ultrasonic vibration-assisted machining is an effective method to deal with difficult-to-machine materials. In this study, ultrasonic elliptical vibration is applied to the helical milling of SiCp/Al composites. Firstly, the ultrasonic elliptical vibration-assisted helical milling (UEVHM) cutting-edge trajectory is modeled, and the equation of the UEVHM tool-chip separation condition is established, which lays a foundation for the analysis of the cutting mechanism. Then, the influence of ultrasonic elliptical vibration on the removal mechanism of SiCp/Al composites was investigated by finite element simulation. It was found that UEVHM can reduce the tearing of aluminum matrix and reduce the hole damage by changing the direction of the cutting velocity and the relative position of the cutting edge and particles. Finally, the single-factor experiment was carried out, and the surface morphology and roughness of HM and UEVHM were compared. The influence of process parameters on the surface roughness of UEVHM was analyzed. The experimental results show that compared with HM, UEVHM can reduce surface defects and exit damage, to obtain better surface roughness and exit edge quality. The increase in cutting speed can reduce the roughness, and the increase in pitch and revolution speed will increase the surface roughness.

Evaluation of grinding performance and removal mechanism of epoxy resin coated single crystal SiC

The inherent hardness and brittleness of single crystal silicon carbide (SiC) materials pose challenges in processing high-quality surface products from SiC. To overcome these challenges, an epoxy resin coated grinding method for SiC was developed and employed in this study. The objective was to investigate how the width (d) and thickness (h) of the epoxy resin coating affect the quality of the ground surface. The research indicated that as d increased from 0 to 2.5 mm, the average surface roughness (Ra) of SiC decreased from 57 to 32 nm. Similarly, as h increased from 0 to 0.8 mm, the average Ra decreased from 53 to 31 nm.

COOLING OF CONTROL RODS AND SPECIFICATION OF CRITICAL TEMPERATURES TO JUSTIFY SAFE OPERATION

The paper analyzes the cooling conditions of the control rods in the mixed core of the WWER-1000 reactor containing fuel assemblies of different vendors (TVSA, WFA/RWFA). The coolant heat-up in the guide thimbles due to own energy release in control rod materials and control rod temperatures required to justify safe operation were calculated for the most conservative case, when the core consists only of TVSAs with a standardized guide thimble inlet plug of NCCP. The energy release was obtained using the calculation method for the boron carbide absorber (B4C), dysprosium titanate (Dy2O3·TiO2), control rod cladding (42CrNiMo), water gap between the cladding and the guide thimble and in the guide thimble (zirconium alloy), fully immersed and 70% immersed RCCA 10th control group. The highest calculated energy release will be observed in fully immersed control rods with boron carbide material at the height position corresponding to the zone of maximum neutron fluence and will be 43.8 W/cm3. The maximum energy release of the 70% immersed (from the bottom of the core) 10th control group is 29.4 W/cm3 for fresh B4C. For the condition of the reactor facility at which the temperatures in FA guide thimbles are maximum, for a "fresh" control rod characterized by maximum energy release in the neutron-absorbing material, the maximum coolant heat-up in the guide thimbles does not exceed 28.9 °C, with the maximum coolant heat-up in FAs being 44 °C, and the maximum control rod cladding temperature not exceeding 335.6 °C at a coolant saturation temperature of 345.8 °C, which indicates that there will be no coolant boiling in the guide thimbles under operation. The maximum temperature typical for the central part of the control rod absorber and for the most conservative calculation for a "fresh" absorber is 529.6 °C, which is significantly lower the melting point of boron carbide, which is ~2350 °C. The maximum calculated temperature in the contact zone of the B4C absorber with control rod cladding is 348 °C. The performed calculations and further analysis of the results confirm that during operation of the RCCA control rods with both “fresh” and “burned-up” B4C, there will be no boiling of the coolant and melting of the absorber in the central part of the control rod. This means that the VVER-1000 core with TVSAs and WFAs/RWFAs and the RCCA rods are reliably cooled.

Lowering Schottky barrier in MoC-based cocatalyst via heteroatoms tunning for enhanced photocatalytic hydrogen evolution

The simultaneous construction of efficient hydrogen evolution surfaces and the establishment of effective electron transport channels are crucial for improving the efficiency of photocatalytic hydrogen evolution reactions (PHERs). Molybdenum carbide materials are considered strong substitutes for Pt co-catalysts in PHERs because their electronic structure is similar to that of Pt. However, it is still challenging to enhance the kinetics of molybdenum carbide for hydrogen evolution reactions (HERs) while improving interface electron transport properties. In this study, low electronegativity heteroatoms P were introduced into metalloid MoC to adjust the overpotential of HERs while tuning the Schottky barrier between MoC and Zn0.5Cd0.5S. Due to the excellent charge separation efficiency in photocatalysts driven by the atomic-scale tuning of interfacial energetics on the prerequisite of not impairing the kinetics for surface reactions, the optimal P-MoC-modified Zn0.5Cd0.5S displayed a hydrogen evolution rate of 28.98 mmol·g−1·h−1, which was 11.59 and 1.51 times higher than that of pure Zn0.5Cd0.5S and Pt-modified Zn0.5Cd0.5S, respectively. This study provides a reference for the design of a high-efficiency co-catalyst and provides a new way for the regulation of the Mott–Schottky barrier.

Preparation of hard magnetic Co2C nanospheres as electrocatalysts for hydrogen evolution reaction

Cobalt carbide as a new type of transition metal carbides (TMACs) has received extensive attention in the field of magnetism and electrocatalysis. As one of the cobalt carbide materials, Co2C shows good hard magnetism. In this paper, we have designed a simple and efficient method to successfully prepare single-phase Co2C nanospheres. Co2C is synthesized by using Co3O4 as precursor and small molecule amino ethylenediamine as carbon source. The material exhibits excellent hard magnetic properties, with saturation magnetization up (Ms) to 32.19 emu/g and coercivity up to 1111 Oe at room temperature. Co2C also demonstrats excellent hydrogen evolution reaction performance in 1 M KOH solution. Using nickel foam as the working electrode, the overpotential of only 92 mV can reach the current density of 10 mA cm−2, and the Tafel slope is 104 mV dec−1. This provides a new idea for the further development of synthetic cobalt carbide and its composite materials.

Study on interface characteristics of WC-Co doped Y rare earth element cemented carbide cutting tool and its influence on material properties

The influence of doping rare earth element Y on the material properties at the W and C interfaces of WC (0001)/Co (111) was studied using first principles calculations, taking into account adhesion work, interface energy, density of states, and Mulliken population. The grain size of WC-Co cemented carbide doped with rare earth element Y was analyzed before and after doping through cellular automata simulation. The microscopic morphology of the cemented carbide materials before and after doping with Y element was observed and analyzed by experiments, and their mechanical properties were tested. The research results have shown that the interface structure doped with Y has smaller interface energy, greater adhesion work, and stronger interface bonding ability. All four interface models exhibit metallic properties, and the addition of Y element enhancing the metallicity of WC-Co. The W-d and Y-p orbitals undergo orbital hybridization and generate covalent bonds, improving the durability and bonding strength of the material. The bond length of C-W at the interface after doping is smaller than that before doping, and the population is greater than that before doping, indicating an enhanced stability of the interface. After the addition of rare earth element Y, the crystals underwent through-crystal fracture, and the fracture showed irregular shapes, which improved the bonding strength of the interface. Through the cellular automata simulation, it was found that the grain size after doping with Y element was significantly smaller than that before doping, and it was experimentally verified that the doping of rare earth element Y played the role of grain refinement. At the same time, it could reduce the coefficient of friction of the material, and improve the overall performance of the cemented carbide material.

(Invited) Insights into the Electrocatalytic Behavior of Mxenes

The continued rise in global energy consumption, along with the associated environmental hazards, pose a significant risk to our society’s infrastructure unless the main source is changed. Electrocatalysis involving hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), and oxygen reduction reaction (ORR), provide a pathway for energy storage and conversion due to their enhanced environmental friendliness and efficient energy input compared to their thermocatalytic counterparts. Currently, the state-of-the-art electrocatalysts suffer from scarcity and high cost. MXenes, a novel family of two-dimensional (2D) transition metal carbide and nitride materials, show potential as cost-efficient and highly abundant electrocatalysts with limited knowledge on their electrocatalytic mechanisms. This is especially true when considering the often-overlooked nitride family of MXenes. Herein, we investigate the electrocatalytic performance of a Ti2N nitride MXene under different electrocatalytic conditions. The effect of surface phenomena is investigated through manipulation of the surface passivation layer, as evidenced by Raman and Fourier-transform infrared (FTIR) spectroscopies, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Successful decoupling of the bulk and surface phenomena is achieved through Raman laser power attenuation. Under acidic medium, the surface reactivity towards HER is poor but the bulk reactivity for NRR is favored, making it an optimal NRR catalyst. Under alkaline medium, the surface reactivity of the pristine Ti2N MXene for ORR is high, but also leads to surface passivation and thus hinders the electrocatalytic activity. Overall, these results provide fundamental insights into future optimization strategies of the Ti2N nitride MXene, along with other MXene electrocatalysts, towards electrocatalytic applications.

A realistic assessment of the prospect that silicon be replaced by other materials for IC application

Silicon is the most significant material in the semiconductor industry, and the whole semiconductor industry is established on silicon materials. Silicon accounts for about a third of the value of the material used to make the entire wafer. However, with the development of the semiconductor industry and integrated circuit chips, the requirements for semiconductor materials are also increasing. In some application scenarios, silicon is gradually unable to meet peoples higher requirements. For example, in high-frequency applications, the characteristics of silicon may be limited. At higher frequencies, the conductivity of silicon may not be ideal, leading to signal delay and performance loss. Therefore, finding alternative materials for silicon has become one of the current research topics for scientists, in order to solve some problems that silicon cannot solve under specific conditions. In this article, we mainly explore the characteristics and advantages of carbon nanotubes, gallium arsenide, and silicon carbide materials to analyze the feasibility of these materials replacing silicon in the field of integrated circuits.

Unusual nanoscale amorphization of metallic chromium interfacing with SiC under high energy irradiation

Layered metal/silicon carbide (SiC) materials systems are becoming increasingly relevant to solve materials challenges in advanced fission and fusion nuclear energy systems, necessitating a deeper understanding of how interfaces between dissimilar materials behave under high energy irradiation. In this work, we use a Cr-SiC bilayer system as a model to study the behavior of such interfaces under high energy ion irradiation (80 MeV Xe26+ ions) at elevated temperatures (∼350 °C). Through high resolution characterization of the interface, we observed the formation of a nanoscale Cr-rich amorphous layer adjacent to crystalline SiC. We explain this phenomenon through a multi-scale computational approach incorporating ballistic mixing simulations, density functional theory calculations, and CALPHAD-based non-equilibrium modeling that shows the localized amorphization of Cr to be driven by the synergistic action of irradiation-induced point defects within Cr and transport of Si and C atoms across the interface. In particular, the accumulation of radiation damage results in the thermodynamic destabilization of the point-defect containing, metastable Cr-Si-C solid solution with respect to an amorphous phase of identical composition. This study advances the understanding of how metal/SiC interfaces behave under irradiation and establishes a modeling framework that can be applied to interfacial systems to understand irradiation-induced amorphization.

Charge transfer effects in (HfNbTiVZr)C—Shown by ab initio calculations and X‐ray photoelectron spectroscopy

AbstractConsidering charge transfer effects and the variability of the bonding between elements with different electronegativity opens up a deeper understanding of the electronic structure and as a result many of the properties in high entropy‐related materials. This study investigates the importance of the diverse bonding and chemical environments when discussing multicomponent carbide materials. A combination of ab initio calculations and X‐ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of multicomponent thin films based on the (HfNbTiVZr)C system. The charge transfer was quantified theoretically using relaxed and nonrelaxed multicomponent as well as binary carbide reference structures, employing a fixed sphere model. High‐resolution XPS spectra from (HfNbTiVZr)C magnetron‐sputtered thin films displayed core‐level binding energy shifts and broadening effects as a result of the complex chemical environment. Charge transfer effects and a changed electronic structure in the multicomponent material, compared with the reference binary carbides, are observed both experimentally and in the density functional theory (DFT) simulations. The observed effects loosely follow electronegativity considerations, leading to a deviation from an ideal solid solution structure assuming nondistinguishable chemically equivalent environments.